Liquid treatment using ultraviolet radiation offers many advantages over other forms of liquid treatment, such as chemical treatment. For example, treatment with ultraviolet radiation does not introduce additional chemical or biological contaminants into the liquid. More specifically, the introduction of chemical components can be hazardous for treatment of medical or biological liquids. Furthermore, ultraviolet radiation provides one of the most efficient approaches to decontamination since there are no microorganisms known to be resistant to ultraviolet radiation, unlike other decontamination methods such as chlorination. Ultraviolet radiation is known to be highly effective against bacteria, viruses, algae, molds and yeasts. For example, a hepatitis virus has been shown to survive for considerable periods of time in the presence of chlorine, but is readily eliminated by ultraviolet radiation treatment. The removal efficiency of ultraviolet radiation for most microbiological contaminants such as bacteria and viruses generally exceeds 99%. To this extent, ultraviolet radiation is highly efficient in eliminating E-coli, Salmonella, Typhoid fever, Cholera, Tuberculosis, an Influenza Virus, a Polio Virus, and a Hepatitis A Virus.
Intensity, radiation wavelength, and duration of radiation are all parameters that have a role in determining the disinfection rate provided by the ultraviolet radiation treatment. These parameters can vary based on a particular target culture. A proper setting of these parameters can ensure that the ultraviolet radiation does not allow microorganisms to develop an immune response, unlike the case with chemical treatments. Furthermore, the parameters set for the ultraviolet radiation will affect biological agents by fusing and damaging the DNA of microorganisms, and preventing their replication. If a sufficient amount of a protein is damaged in a cell of a microorganism, the cell enters apoptosis or a programmed death.
Ultraviolet radiation disinfection using mercury based lamps is a well-established technology that has been used with ultraviolet treatment systems. In general, an ultraviolet treatment system for treating water using ultraviolet radiation is relatively easy to install and maintain in a plumbing or septic system. Use of ultraviolet radiation in such systems does not affect the overall system. However, it is often desirable to combine an ultraviolet purification system with another form of filtration since the ultraviolet radiation cannot neutralize chlorine, heavy metals, and other chemical contaminants that may be present in the liquid. Various membrane filters for sediment filtration, granular activated carbon filtering, reverse osmosis, and/or the like, can be used as a filtering device to reduce the presence of chemicals and other inorganic contaminants.
Mercury lamp-based ultraviolet radiation treatment systems have several shortcomings when compared to deep ultraviolet (DUV) light emitting device (LED)-based technologies, particularly with respect to certain disinfection applications. For example, in rural and/or off-grid locations, it is desirable for an ultraviolet purification system to have one or more various attributes such as: a long operating lifetime, contain no hazardous components, not be readily susceptible to damage, require minimal operational skills, have no required special disposal procedures, be capable of operating on local intermittent electrical power, and/or the like. Use of a DUV LED-based solution can provide a solution that improves one or more of these attributes as compared to a mercury vapor lamp-based approach. For example, in comparison to mercury vapor lamps, DUV LEDs can have substantially longer operating lifetimes (e.g., by a factor of ten); do not include hazardous components (e.g., mercury), which require special disposal and maintenance; are more durable in transit and handling (e.g., no filaments or glass); have a faster startup time; have a lower operational voltage; are less sensitive to power supply intermittency; are more compact and portable; can be used in moving devices; can be powered by photovoltaic (PV) technology, which can be installed in rural locations having no continuous access to electricity and having scarce resources of clean water; and/or the like.